Unwinding means for threads, cords, and the like



1956 A. E. HERBERT ET AL 2,768,797

UNWINDING MEANS FOR THREADS, CORD S, AND THE LIKE 2 Sheets-Sheet 1 FiledApril 22, 1952 Oct. 30, 1956 A, E. HERBERT ET AL 2,768,797

UNWINDINGMEANS FOR THREADS, CORDS, AND THE LIKE Filed April 22, 1952 2Sheets-Sheet 2 NVENTORS: A RED Eowm HERBERT; TosEPH wows mp Rial-mapTURNER Mag raw United States Patent 0.

MEANS FOR THREADS, CORDS,

AND THE LIKE Alfred Edwin Herbert, Joseph Woods, and RichardTurner,,Rochda1e, England, assignors to John Bright & Brothers Limited,Rochdale, England Application April 22, 1952, Serial No. 283,561 Claimspriority, application Great Britain May 3, 1951 2 Claims. (Cl. 242156)sary to stretch it so that fabrics into which it is woven shall be of aspecified stretch, or at least shall not stretch so much as they wouldif the cord were used just as .it is spun or twisted and not stretched..-It will be understood that to this end it is necessary that the cord,and, all of it, if possible, shall be evenly stretched or elongated, butstretching machines as used at present do not produce an even stretch orelongation, and this may apply more particularly to cords produced byring twisting.

In machines of the kind to which this invention applies, the spun ortwisted cord, on a bobbin, is mounted on the machine, and the cord,after passing round a pair of grooved rollers, with conical parts onthem, which are the stretching rollers, is led to a bobbin above,mounted horizontally and rotated by contact with a driven roller onwhich it rests. In this way the end of the [cord from the full, orlet-off bobbin below is attached to the empty bobbin above so that asthe top bobbin fills, the other empties and consequently the speeds andweight of the bobbins are varying throughout the operation, and thestretch also varies, but tests have shown that at the beginning of arun, the tension on the cord is much less than the tension at the end ofthe run, and consequently there is a higher elongation or greaterstretch toward, and at, the end of the winding than at the beginning.

Some existing machines are provided with a swinging weight acting as abrake on the bottom bobbin but the construction and operation have notbeen successful in progressively regulating the tension of the cordbeing wound off. It was believed that a more even stretch could beobtained by controlling the rotational speeds of the bobbins andexperiments were made to test this theory. To some extent it was foundcorrect, more particularly with regard to the bottom bobbin, which itwill be understood is an idler from which the cord is drawn, but it wasnot quite the same with the top bobbin, where it was believed, theincreasing weight was a factor of difiiculty in that, the frictionalengagement of the top bobbin with its driving roller below must varywith the weight. Probably the changing diameters of the bobbins also hasan effect on the tension and stretch.

Accordingly further tests and experiments were made which resulted in aconstruction which is the subject of this invention, and according tothe invention, in a stretching frame for cords the stretch of the cordis made more even, by applying to the bottom or take-off bobbin a brakewhich applies a declining pressure as the Patented Oct. 30, 1956 bobbinempties and applying to the top bobbin a weight which declines as thebobbin fills.

The invention is more particularly described with reference to theaccompanying drawings in which Fig. 1 is a side view of the take-0Ebobbin bracket fitted with braking mechanism for the bobbin according tothe invention.

Fig. 2 is 'anend view from the right of Fig. 1, and

Fig. 3 is adiagrammatic view showing how rotation of the top or take-upbobbin is controlled.

As shown in the drawings and referring first to Figs. 1 and 2, thebottom or take-off bobbin bracket 4 is mounted to the machine frame bybolts 5. The bobbin, whose position is shown by dotted lines in Fig. 1is supported at an incline between the arms of bracket 4, and rotates ona cone-bearing 6 at the lowerend, and a spring-loaded plunger '7 at theother end, which arrangement affords thequick removal and mounting ofbobbins.

Mounted on the limbs of the bracket 4 at the side are upstandingsupports 8 and '9 respectively, and these are adjustable laterally forwhich purpose each is secured to the bracket by bolts 10, 7 individualadjustment being eifec-ted by mounting washers 11 of the desiredthickness on the bolts between the bracket and the supports themselves-as shown in Fig. 2.

Pivoted at 12 and 13 to the supports 8 and 9 respectively are-arms 14which project from a weighted member 15 having a braking surface 16which engages the surface of the bobbin or the surface of cord woundthereupon. Pivots 1'2 and 13 are not located in the vertical planepassing through the axis of the bobbin but are to one side of it, andthe arms 14 are curved so that the weighted member 15 always swingsinwardly to engage the bobbin, the pressure it exerts on the bobbindeolinin'g as the centre of gravity of the weighted member 1 5 swingsmore nearly to a vertical position under the pivots 12 and 13 which isof course as the bobbin empties. The bobbin is not shown in Fig. 2 butthe weighted member 15 is shown in the position it occupies when thebobbin is partially unwound.

When the bobbin is nearly empty, it is desirable to remove the brakingpressure entirely and to this end the weighted member 15 is formed witha bifurcated tail 17 which moves astride a fixed peg 18 projecting froma web 19 on the bracket 4. On this peg is a compression spring 20bearing against a washer 21 also on the peg, so that as the weightedmember 15 swings gradually inward under its own weight the tail 17 movesastride the peg 18, engages the washer 21 and tends to compress thespring after it has moved inwardly for a predetermined distance. Whenthe Washer is first encountered by the tail of the weighted member, thespring is first compressed slightly, but as the pressure increases, thespring reaction likewise increases until the spring is fully compressedwhereupon the weighted member is held against further movement and doesnot apply any braking effect to the rotary bobbin.

It will be appreciated that lateral adjustment of supports 8 and 9 iscritical with respect to the amount of braking pressure appliedthroughout, since this is largely dependent on the positions of pivots12 and 13, in relation to the bobbin axis.

Rotation of the top or take-up bobbin is controlled in a differentmanner, as here the speed is not the only factor to be directlygoverned.

It has already been pointed out that as the weight of the top bobbinincreases so does its frictional engagement with its driving rollerbelow increase, and for this reason the control on the top bobbin is inthe form of a weight control, illustrated diagrammatically in Fig. 3,which shows the positions of the bobbin and weighting means at twostages of the operation.

As shown in Fig. 3 there is pivoted at a point 22 behind the frictionroller 23 a bell-crank lever 24 having weights 25 and 26 respectively atits ends. The lever 24 is so pivoted that, when the bobbin 27 is emptyone arm is vertical and the other horizontal, the weight on thehorizontal arm lying on the bobbin in front of a vertical plane throughthe bobbin axis. In Fig. 3 this position is shown by full lines.

As cord is wound on the bobbin, weight 25 is lifted by the cord as thediameter increases and the vertical arm is gradually tilted back to thechain-dotted position so that weight 26 begins to counteract Weight 25which rests on the cord. This movement continues until the moment ofweight 26 exceeds the counter-moment of weight 25 whereupon weight 26swings over and lifts weight 25 completely off the bobbin. Provision ismade of course for the bobbin axis to rise along a line radial to thefriction roller 23 as the cord builds up.

The weights 25 and 26 can be made adjustable or detachable so that theleverage can be adjusted to ensure that the latter weight is liftedclear at correct time, that is when the bobbin, including the cord woundon it, is itself heavy enough to provide the desired pressure between itand the driving roller; and the weight 25 may be in the form of aroller.

It is found that by using the adjustable brake on the bottom bobbin, andthe adjustable weight on the top bobbin as described, a more evenstretch can be imparted to the cord than has been hitherto obtained.

We claim:

1. In a stretching frame for cords, threads and the like, a U-shapedbracket for each take-off bobbin, and braking means applied to saidbobbin, said braking means comprising a pivoted member normally engagingthe bobbin under its own weight, a bifurcated projection on said pivotedmember, a peg on said bobbin bracket astride of which peg saidbifurcated projection moves, and a spring on said peg, said spring beingcompressed by said projection as the bobbin empties so as to counteractthe gravitational pressure of said pivoted member on the bobbin, saidspring becoming fully compressed before the bobbin empties so as to holdsaid pivoted member out of contact with the bobbin, and relieve thebraking pressure exerted thereon, during the final stage of unwinding.

2. For use with a let-oflf bobbin, a braking device comprising, incombination, supporting means including bearing means for supporting thelet-off bobbin; weighted downwardly extending lever means pivotallysupported on said supporting means at a pivoting point located abovesaid bearing means, said weighted lever means having a portion adaptedto be supported by and thereby frictionally engage the let-ofi bobbinfor braking the same, and being adapted to turn from a first higherbraking position to a second lower braking position for reducing thebraking pressure on the let-01f bobbin as a diameter of the let-01fbobbin is reduced due to winding off of thread; and stop means engagingand holding said weighted lever means in said second braking positionwhereby the let-01f bobbin is relieved from braking pressure when thediameter thereof further decreases due to winding ofi of thread.

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